322 THE SURVIVAL OF THE UNLIKE. [XIX. 



The subject at once divides itself into two heads, 

 and each head divides into two minor captions : * 



I. Acclimatization through a change in the indi- 

 vidual plant. 



A. Modification of constitution. 



B. Modification of habit. 



II. Acclimatization through a variation in offspring. 



A. Variation in constitution. 



B. Variation in habit. 



I. A. There is very little record of experience con- 

 cerning individual adaptation to climate, and nearly 

 all the record which does exist is negative. It is an 

 almost universal opinion that the same plant cannot 

 become modified in constitution so as to endure an 

 injurious climate. Such opinion is not strange if we 

 recollect that the same observer seldom knows the 

 plant in both its original and adopted homes, and is 

 therefore unable to determine if it has a(*quired any 

 hardiness. Moreover, such change in individual consti- 

 tution is looked for in plants which have been removed 

 through a great latitude of climate. The fact that 

 plants thus removed usually suffer severely or die out- 

 right has given rise to the opinion that such acclimati- 

 zation does not exist. Yet, although it is difficult to 

 demonstrate individual constitutional adaptation, I am 

 prepared to believe that changes may occur in plants 

 which are removed through small distances,' say a de- 

 gree or so. But the subject is so difficult of determina- 

 tion that we shall not be likely to be speedily enlight- 



•Some writers contend that acclimatization takes place through the agency of 

 hybridization, but as hybrids are in reality entirely new productions, lying out- 

 side the species, they cirnnot properly be considered tinder tliis subject. 



